This project will utilize psychophysiologic techniques to assess the responses of Chernobyl disaster workers and Afghanistan war veterans during imagery of their personal past traumatic experience. Subjects will be diagnosed into post-traumatic stress disorder (PTSD) and non-PTSD groups, matched with regard to age, time elapsed since the index trauma, severity of traumatic exposure, and comorbid mental disorders. The project will be performed at the Laboratory for Traumatic Stress Studies, Institute of Psychology, Russian Academy of Sciences, Moscow, under the direction of Nadja V. Tarabrina, Ph.D. Thirty-second "scripts" will be prepared with the aid of the subject describing various past life experiences, including the specific traumatic experiences to be studied. The scripts will incorporate subjective visceral and muscular reactions that the subject remembers accompanied each experience. The scripts will be recorded for playback in the laboratory. The subject will be instructed to imagine the events the scripts portray, while heart rate, skin conductance, and facial muscle electromyograms are recorded. The data will be analyzed by means of two-factor (Trauma, Diagnosis) multivariate analysis of variance (MANOVA). In addition, the physiologic responses of the Russian PTSD and non-PTSD subjects will be compared with the responses of military and civilian PTSD and non-PTSD trauma survivors already studied with the same methodology in the U.S.A. and Israel. The success of a discriminant function derived from these earlier subjects in classifying Russian PTSD and non-PTSD subjects will be examined. The significance of the work to be performed is two-fold. First, it will extend research into an important mental health problem, i.e., PTSD, to a new cultural population of Russian nuclear disaster workers and war veterans. Second, it will apply a proven psychophysiologic research technique to the previously unstudied question of the effect of "invisible" psychological trauma, in this case the possibility of harm from nuclear radiation.